W124 300D stater/solenoid replacement
02-09-2014, 10:22 AM
#1
Junior Member
Thread Starter
W124 300D starter/solenoid replacement
I couldn't find a thread on this subject, so I decided to write one up.
Every once in a while, my starter would whir and not engage. On the next try, the car would start normally. The problem increased in frequency. I (incorrectly) assumed it was the starter solenoid.
To replace the solenoid (cheaper than a whole starter) you need to remove the starter and secure it in a vise. The three screws that hold the solenoid to the starter have red thread lock at the base. You need to be able to bear down with a good philips screwdriver. Once you break the screws free they come out easily and the solenoid pops off.
Now getting the starter off a diesel is another matter. Jumping Jahosaphat, what an ordeal
. But it can be done. And the job is somewhat easier when you have to do it a second time after you've buttoned everything up to discover that despite a new solenoid the starter is still bad 
.
AutohausAZ had the best price on a rebuilt Bosch starter, $186 (plus core charge).
The removal procedure from the Haynes manual worked for me.
The complication on the turbo-diesel models is that the transmission coolant hard lines and a tangle of fuel lines are smack in the way.
In order to get the starter off the engine and out from under the car, you have to remove the steering linkage and jack the engine up to get just barely enough room to get the starter out.
Steering linkage removal:
1) Set the parking brake. Jack the car up on both sides and lower it securely onto jack stands. You're going to spend some quality time lying on your back under the car.
2) remove the steering damper. You'll need a 17mm socket (I think) and also a wrench for the bolt/nut assembly on the driver's side. When you reinstall, the fatter end of the steering damper goes on the driver's side.
3) remove the linkage. The nuts on top of the linkage come off fairly easily. I used a ratchet. There is very little room to work on the driver's side. I came at it through an opening to the left of the nut near the wheel. There is more room on the passenger's side. You will need a small pickle fork and a BFH to release the steering linkage from the knuckles. Fortunately the boot material is very sturdy. The pickle fork did no damage.
Check the condition of the steering linkage, boots, and damper since you have them off. When you reinstall, clean the holes in the knuckle and the shafts of the joints before reinstalling. I had to tap the bits together several times to get the shaft to seat so the nut would tighten--otherwise it just turns and turns. Haynes did not have a torque spec for the nuts (and you can't get a torque wrench on them anyway), so i just made sure they were good and tight.
4) Prepare to lift the engine. There are two bolts (18mm, I think) that hold the round rubber engine mounts from the bottom. They are accessible through a hole. Use a long socket or a short one with a short extender. They come out easily and that's all you have to remove to lift the engine. Per Haynes, torque to 30 ft lbs when you reinstall the bolts.
5. Disconnect the wiring from the solenoid--Do this while the starter is still attached to engine (ask me how I know). This is the really fun part
. There is no room to work and it is dark as sin.
Get as much light on the subject as possible. I used a small LED light. Pull the rubber cover over the nut back as far as you can. It will of course slip back and block your light and get in the way. There is a large wire secured with with a 13mm nut and a small wire secured with a phillips screw. I used a small ratchet and a long socket to loosen and remove the nut and washer. Due to the tangle of fuel and coolant lines, there is NO, repeat NO, room to get a normal sized or even an extra long screwdriver on the philips screw. A stubby screwdriver was the only thing that worked.
6) Unbolt the starter. There are two long bolts that hold the starter to the engine opposite the starter, one on the top and another on the bottom. Start with the one on top. You have to do this by feel, but there is enough room to work a ratchet and socket. Repeat for the bottom bolt. On reinstalling, there wasn't a torque spec, so I made sure the bolts were good and snug.
The starter comes straight out. Now you will discover that the fuel and coolant lines make it impossible to get enough clearance to get the starter out.
7) Lift the engine. Put a pice of wood on a hydraulic jack and put it under the oil pan. Jack up the engine. You will just be able to get enough room to squeeze the starter in and out. It comes out from the bottom of the car. I tipped it up and eased the rounded piece at the bottom of the starter from the hole. On reinstalling, the rounded piece faces the driver's side so the gears exposed on the other side will mate up.
8) Lower the engine and reassemble. Bolt the starter back on. Attach the wires, making sure the nut and screw are tight and make good contact (otherwise the car won't start
). Reinstall the bolts to the motor mounts. By the way, you have to lift the engine like this to replace the motor mounts, so you might plan to do that job at the same time. (N.B. when I replaced my motor mounts, PartsGeek had the best price on OES Lemforder mounts). Replace the steering linkage and damper. Double check that everything is back where is supposed to be and properly tightened. Lower the car, get in, wait for the glow plug light to go out, say a prayer, and give the ignition key a turn. You should be rewarded with a crisp start up.
Hopefully I got a got a good rebuilt starter because I don't ever want to have to do this again.
Every once in a while, my starter would whir and not engage. On the next try, the car would start normally. The problem increased in frequency. I (incorrectly) assumed it was the starter solenoid.
To replace the solenoid (cheaper than a whole starter) you need to remove the starter and secure it in a vise. The three screws that hold the solenoid to the starter have red thread lock at the base. You need to be able to bear down with a good philips screwdriver. Once you break the screws free they come out easily and the solenoid pops off.
Now getting the starter off a diesel is another matter. Jumping Jahosaphat, what an ordeal
. But it can be done. And the job is somewhat easier when you have to do it a second time after you've buttoned everything up to discover that despite a new solenoid the starter is still bad .AutohausAZ had the best price on a rebuilt Bosch starter, $186 (plus core charge).
The removal procedure from the Haynes manual worked for me.
The complication on the turbo-diesel models is that the transmission coolant hard lines and a tangle of fuel lines are smack in the way.
In order to get the starter off the engine and out from under the car, you have to remove the steering linkage and jack the engine up to get just barely enough room to get the starter out.
Steering linkage removal:
1) Set the parking brake. Jack the car up on both sides and lower it securely onto jack stands. You're going to spend some quality time lying on your back under the car.
2) remove the steering damper. You'll need a 17mm socket (I think) and also a wrench for the bolt/nut assembly on the driver's side. When you reinstall, the fatter end of the steering damper goes on the driver's side.
3) remove the linkage. The nuts on top of the linkage come off fairly easily. I used a ratchet. There is very little room to work on the driver's side. I came at it through an opening to the left of the nut near the wheel. There is more room on the passenger's side. You will need a small pickle fork and a BFH to release the steering linkage from the knuckles. Fortunately the boot material is very sturdy. The pickle fork did no damage.
Check the condition of the steering linkage, boots, and damper since you have them off. When you reinstall, clean the holes in the knuckle and the shafts of the joints before reinstalling. I had to tap the bits together several times to get the shaft to seat so the nut would tighten--otherwise it just turns and turns. Haynes did not have a torque spec for the nuts (and you can't get a torque wrench on them anyway), so i just made sure they were good and tight.
4) Prepare to lift the engine. There are two bolts (18mm, I think) that hold the round rubber engine mounts from the bottom. They are accessible through a hole. Use a long socket or a short one with a short extender. They come out easily and that's all you have to remove to lift the engine. Per Haynes, torque to 30 ft lbs when you reinstall the bolts.
5. Disconnect the wiring from the solenoid--Do this while the starter is still attached to engine (ask me how I know). This is the really fun part
. There is no room to work and it is dark as sin.Get as much light on the subject as possible. I used a small LED light. Pull the rubber cover over the nut back as far as you can. It will of course slip back and block your light and get in the way. There is a large wire secured with with a 13mm nut and a small wire secured with a phillips screw. I used a small ratchet and a long socket to loosen and remove the nut and washer. Due to the tangle of fuel and coolant lines, there is NO, repeat NO, room to get a normal sized or even an extra long screwdriver on the philips screw. A stubby screwdriver was the only thing that worked.
6) Unbolt the starter. There are two long bolts that hold the starter to the engine opposite the starter, one on the top and another on the bottom. Start with the one on top. You have to do this by feel, but there is enough room to work a ratchet and socket. Repeat for the bottom bolt. On reinstalling, there wasn't a torque spec, so I made sure the bolts were good and snug.
The starter comes straight out. Now you will discover that the fuel and coolant lines make it impossible to get enough clearance to get the starter out.
7) Lift the engine. Put a pice of wood on a hydraulic jack and put it under the oil pan. Jack up the engine. You will just be able to get enough room to squeeze the starter in and out. It comes out from the bottom of the car. I tipped it up and eased the rounded piece at the bottom of the starter from the hole. On reinstalling, the rounded piece faces the driver's side so the gears exposed on the other side will mate up.
8) Lower the engine and reassemble. Bolt the starter back on. Attach the wires, making sure the nut and screw are tight and make good contact (otherwise the car won't start
). Reinstall the bolts to the motor mounts. By the way, you have to lift the engine like this to replace the motor mounts, so you might plan to do that job at the same time. (N.B. when I replaced my motor mounts, PartsGeek had the best price on OES Lemforder mounts). Replace the steering linkage and damper. Double check that everything is back where is supposed to be and properly tightened. Lower the car, get in, wait for the glow plug light to go out, say a prayer, and give the ignition key a turn. You should be rewarded with a crisp start up.Hopefully I got a got a good rebuilt starter because I don't ever want to have to do this again.
Last edited by CCMcC; 02-13-2014 at 02:06 PM. Reason: Corrections
02-28-2014, 09:09 PM
#4
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1987 Mercedes-Benz 300D
starter removal
I appreciate your helpful post. I had hoped the process would be easier, but no such luck. I thought getting the bolts off of the starter itself was difficult enough, but actually removing it is a whole other mission. During the past two weeks when I would attempt to turn over the ignition I would occasionally get a 'click,' instead of it actually turning over. However when it does turn over it starts instantly. Battery connections are good so I'm ruling that out. I sure hope after I somehow get the starter out that that truly is the problem.
04-19-2020, 12:13 PM
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W124 OM603.960, 1991 300 TDT
Thanks for the post. I got a bit frightened and was not looking forward to lift the engine...
Turned out that it was much easier on my model 91 W124 300 TDT. Only had to remove the windscreen wiper fluid tank. That gave fairly easy access to the electrical connections from the top.
The bolts holding the starter were fairly accessible from below, the lower one is easy, the top one you can actually see when looking from the correct angle. I used a slightly shorter key there, giving me enough space to make quarter turns.
Getting the starter out was easy following the advice from here. "You will need to move the starter around and bring it out from the bottom electrical end first."
In my case the symptoms were: not able to start, no sound, not even clicking. Checked first all electrical connections / battery and concluded that there was something wrong with the starter itself. When I had pulled it out I tested it directly on the battery and it seemed to work fine. Anyway, I took the starter apart (easy job) ,cleaned it and filled up with grease. Both the planetary gear and the grease cap at the other end were out of grease. It was a Valeo starter and probably not the original that came with the car.
Put all together in reverse order and problem solved
Turned out that it was much easier on my model 91 W124 300 TDT. Only had to remove the windscreen wiper fluid tank. That gave fairly easy access to the electrical connections from the top.
The bolts holding the starter were fairly accessible from below, the lower one is easy, the top one you can actually see when looking from the correct angle. I used a slightly shorter key there, giving me enough space to make quarter turns.
Getting the starter out was easy following the advice from here. "You will need to move the starter around and bring it out from the bottom electrical end first."
In my case the symptoms were: not able to start, no sound, not even clicking. Checked first all electrical connections / battery and concluded that there was something wrong with the starter itself. When I had pulled it out I tested it directly on the battery and it seemed to work fine. Anyway, I took the starter apart (easy job) ,cleaned it and filled up with grease. Both the planetary gear and the grease cap at the other end were out of grease. It was a Valeo starter and probably not the original that came with the car.
Put all together in reverse order and problem solved
